Stacker and method of stacking frozen food patties

ABSTRACT

A stacking method and apparatus for frozen food patties and like disc-shaped articles; the patties are discharged in free fall and at predetermined speed over the terminal end of an input conveyor and are accumulated on a stationary stacking conveyor after rotation of about 180*, being guided into an orderly stack by a guide positioned outwardly of the terminal end of the input conveyor. The stack height is monitored, preferably by counting the patties; when a full stack is collected, the guide is lifted up and away from the stacking conveyor and the stacking conveyor is actuated to move the stack away from the stacking position. The guide is moved back to its original position and the stacking conveyor is stopped before the next patty falls onto the stacking conveyor.

United States Patent [1 1 Carbon et al.

[ 51 Feb. 18,1975

[73] Assignee: Formax, Inc., Mokena, Ill.

[22] Filed: June 21, 1973 [21] Appl. No.: 372,236

[52] US. Cl. 198/35 [51] Int. Cl B65g 57/00 [58] Field of Search 198/35;271/DIG. 7;

. 93/93 C, 93 DP; 214/6 D [56] References Cited UNITED STATES PATENTS11/1930 Otis 198/35 7/1953 Winters 198/35 6/1965 Hartbauer et al.....271/DIG. 7

Primary Examiner-James B, Marbert Assistant Examiner-Douglas D. WattsAttorney, Agent, or Firm-Kinzer, Plyer, Dorn & I McEachran [5 7]ABSTRACT A stacking method and apparatus for frozen food patties andlike disc-shaped articles; the patties are discharged in free fall andat predetermined speed over the terminal end of an input conveyor andare accumulated on a stationary stacking conveyor after rotation ofabout 180, being guided into an orderly stack by a guide positionedoutwardly of the terminal end of the input conveyor. The stack height ismonitored, preferably by counting the patties; when a full stack iscollected, the guide is lifted up and away from the stacking conveyorand the stacking conveyor is actuated to move the stack away from thestacking position. The guide is moved back to its original position andthe stacking conveyor is stopped before the next patty falls onto thestacking conveyor.

10 Claims, 8 Drawing Figures STACKER AND METHOD OF STACKING FROZEN FOODPATTIES BACKGROUND OF THE INVENTION Pre-molded food patties,particularly hamburger patties, have found increasing popularity forboth commercial and household use. A number of different highspeedhigh-volume devices have been developed for the manufacture of thesefood patties. To obtain the advantages of centralized production,increasingly larger percentages of hamburger patties and other foodpatties are being marketed in frozen form. In a typical installation,the patties are molded in a high speed molding machine, conveyeddirectly into and through a cryogenic freezing tunnel, and then packagedfor distribution to commercial and retail outlets. The frozen pattiesare hard and brittle, as they emerge from the cryogenic freezingequipment, and must be maintained in frozen condition throughout anypackaging or subsequent processing.

For the most part, hand stacking and packaging has been employed forfrozen hamburgers and other food patties, even in high-volume productionfacilities. This often requires a substantial number of stackeremployees, adding considerably to the expense of overall plantoperation, particularly for a plant in which molding and freezing of thepatties is a fully automated operation. Hand stacking is a ratherunpleasant job, since the patties are frozen and difficult to handle.Any inaccuracy in the stacking operation may result in an economic lossto the plant operator, either from customer complaints or from deliveryof excess goods to the customers. Substantial floor space may berequired, in a high speed frozen food patty processing line, in order toafford adequate work room for the stackers. Any frozen patties that aredropped represent an economic loss, due to breakage and the loss ofsanitary control.

In many installations, it is highly desirable to afford a completein-line operation from the patty molding equipment through therelatively long cryogenic freezing tunnel and then through the packagingoperation. Any deviation from a direct linear processing path maymaterially increase floor space requirements, particularly ininstallations in which more than one processing line is employed.

Several different forms of equipment have previously been proposed forstacking disc-shaped articles. For example, in the tortilla stackershown in Mason patent No. 3,393,645 tortillas slide down a chute and areprojected out along a horizontal extension of the chute, coming to restin a stack that accumulates on a set of movable plates. The plates areretracted when the stack is complete, allowing the tortillas to fallonto an output conveyor. In another stacker, shown in Maulini US. Pat.No. 3,338,370, biscuits are discharged at relatively high speed from thebottom of a hopper, either in pairs or on an individual basis; arelatively complex multiple hopper arrangement is used to develop stackscontaining a plurality of biscuits.

Another biscuit stacker is Morton US. Pat. No. 3,282,399 in whichbiscuits slide off of the end of a plate at high speed and fly outwardlyinto engagement with an anvil. From the anvil, the biscuits falldownwardly to accumulate on an output conveyor. In the Mortonarrangement, the biscuits turn through a limited angle, less than 90.Another stacker that utilizes a turning motion of about is shown inMonaco U.S. Pat. No. 2,519,419, in which the biscuits or like articlesslide off of the end of an upwardly inclined conveyor and down a guidechute to accumulate in a vertically oriented stack.

An entirely different form of stacker is shown in Joa US. Pat. Nos.3,324,930 and 3,391,777. In these mechanisms, the flat objects to bestacked are carried upwardly away from an input conveyor by a transferconveyor that deposits the articles on an output conveyor. The transferconveyor rotates the articles through an angle of in an operating cyclethat maintains the transfer conveyor in contact with the articlesthroughout the stacking operation.

Each of these previously proposed stacking devices presents somedisadvantage and difficulty when applied to the stacking of hard,brittle, disc-shaped articles such as frozen food patties. Some of thestackers require the use of relatively high conveyor speeds in thestacking operation, particularly where the stacked articles aremaintained in the same angular orientation throughout the stackingoperation. This high speed operation presents a substantial possibilityof damage, when the movement of the articles isinterrupted by an anvilor other blocking member. In several instances, the stacking equipmentis relatively complex, unduly increasing the cost and presenting amaintenance prob lem in the rather difficult environment presented by afood processing plant. I-land stacking, on the other hand, is expensive,potentially inaccurate, and entails the use of excessive amounts offloor space.

SUMMARY OF THE INVENTION It is a principal object of the presentinvention, therefore, to provide a new and improved stacker apparatusand stacking method, applicable to the stacking of fro zen food pattiesand other similar disc-shaped articles in high-volume productionfacilities, that does not require the utilization of high speedconveyors and can be operated effectively at relatively low conveyorspeeds.

A particular feature of the present invention is the provision of ahigh-volume stacking method and apparatus, operable with conveyorsfunctioning at relatively low speeds, in which stacking is effectedthrough free fall of the stacked articles through a relatively shortdistance, entailing a rotation of approximately 180 and continuous butlimited guidance of the articles during the stacking process.

Another object of the invention is to provide a highv speed operatingmechanism for displacing a guide, in a free-fall stacker for frozen foodpatties and like discshaped articles, that removes the guide to permitthe transport of a completed stack away from the stackinglocation andsubsequently restores the guide to its normal guiding position beforethe first article for the next stack reaches the stacking location.

Another object of the invention is to provide a new and improved methodand apparatus for monitoring the accumulation of-frozen food patties orlike discshaped articles in the course of stacking those articles forpackaging at the output of a high volume production line.

A particular object of the invention is to provide a new and improvedstacker for frozen food patties or like disc-shaped articles that issimple and economical in construction, requires a minimum ofmaintenance,

and is adapted to use in a straight-line production arrangement.

Accordingly, the invention relates to a stacker for stacking frozen foodpatties or like disc-shaped articles; the stacker comprises asubstantially horizontal input conveyor, having a terminal end locatedat a stacking station, for conveying frozen food patties or likediscshaped articles to the stacking station at a predetermined speed andwith predetermined minimum spacing, the input conveyor discharging thearticles in free fall over its terminal end. A normally stationarystacking conveyor extends outwardly of the stacking station from astacking location below the terminal end of the input conveyor, thevertical distance from the terminal end of the input conveyor to thestacking conveyor being sufficient to allow each article to rotatethrough an angle of about 180 as it falls toward the stacking conveyor.A guide, movable between a stack guidanace position adjacent thestacking conveyor and a stack release position displaced from thestacking conveyor, is employed to guide the articles to accumulate in anorderly stack on the portion of the stacking conveyor at the stackinglocation. Stacking conveyor actuating means are provided, actuating thestacking conveyor for a limited time interval, not substantially greaterthan the time interval between discharge of successive patties into thestacking station, to transport an accumulated stack of patties away fromthe stacking location. Further, guide actuatingmeans are provided toactuate the guide from its stack guidance position to its releaseposition and back again in timed relation to operation of the stackingconveyor actuating means, the guide returning to its back guidanceposition before more than one patty for the next stack reaches thestacking conveyor.

The invention further relates to a method of stacking frozen foodpatties and like disc-shaped articles. In the stacking method, a seriesof disc-shaped articles are conveyed in flat, spaced, longitudinalalignment at a predetermined speed along a given generally horizontalinput path toward a terminal end of the path; the articles aredischarged, successively, in free fall, from the terminal end of theinput path and into a stacking station. The falling articles arecollected in a stack on a normally stationary conveyor surface at thestacking station, below the terminal end of the input path, the verticaldistance from the terminal end of the input path to the stackingconveyor surface being sufficient to allow each article to rotatethrough an angle of about 180 as it falls. The articles are guided intoan orderly stack by normally maintaining a guide in a guidance positionadjacent the stacking conveyor surface and spaced outwardly of theterminal end of the input path. The height of the stack of articlesaccumulating on the stacking conveyor surface is continuously monitored,and the guide is moved upwardly of the stacking conveyor surface andoutwardly of the terminal end of the input path to a stack releaseposition upon accumulation of a stack of given height. The stackingconveyor surface is moved to transport the stack away from the stackinglocation, substantially simultaneously with movement of the guide towardits release position. The guide is restored to its guidance position andmovement of the stacking conveyor is stopped before the next articlereaches the stacking conveyor.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation view of apatty stacker constructed in accordance with one embodiment of thepresent invention and capable of carrying out the stacking method of theinvention;

FIG. 2 is a plan view of the stacker of FIG. 1;

FIG. 3 is an end view, taken from the output end, of the stacker ofFIGS. 1 and 2;

FIG. 4 is a partly schematic elevation view of the stacking station inthe stacker of FIGS. 1-3, drawn to an enlarged scale and employed toexplain the stacking operation; I

FIG. 5 is a detail view, partly schematic, taken approximately alongline 5-5 in. FIG. 4, illustrating the monitoring apparatus for thestacker;

FIG. 6 is a side elevation view of the stacking station for the stackerof FIGS. 13, drawn to an enlarged scale, with the covers of a part ofthe apparatus removed to show details of the operating mechanism;

FIG. 7 is a detail end elevation. view of the stacking mechanism of FIG.6, with covers cut away to show the operating mechanism; and

FIG. 8 is a detail sectional view taken approximately along line 8-8 inFIG. 7.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The general construction of astacker 10 for stacking frozen food patties or like disc-shapedarticles, comprising one embodiment of the present invention, is shownin FIGS. 1-3. Stacker 10 includes an input conveyor 11 mounted on aframe 12 and located in align ment with the output end of productionapparatus, such as a cryogenic freezing tunnel 13, in position toreceive frozen food patties discharged from a conveyor 14 within theproduction equipment.

The input conveyor 11 is substantially horizontal in alignment, althoughsome deviation from the horizontal can be permitted as indicated inFIG. 1. The terminal end 15 of conveyor 11 is located at a stackingstation 20. A stacking conveyor 21, mounted upon a frame 22, is includedin stacker 10. The stacking conveyor 21 extends outwardly of stackingstation 20, away from a stacking location 23 below the terminal end 15of input conveyor 11. Input conveyor 11 operates at a predetermined,constant speed and the stacking location 23 on output conveyor 21 isspaced below the terminal end 15 of input conveyor 11 by a verticaldistance which is sufficient to allow each patty to rotate through anangle of in free fall, as described in greater detail hereinafter.

Stacker 10 includes a guide 24 that is normally maintained in a stackguidance position, as shown in FIGS. 1 and 3, adjacent the surface ofthe stacking conveyor 21. Guide 24 is spaced outwardly a short distancefrom the terminal end 15 of input conveyor 11. Guide actu-' ating means,generally identified by reference numeral 25, are provided for actuatingguide 24 from its normal stack guidance position to a release position.This movement of guide 24 is in a direction upwardly from stackingconveyor 21 and somewhat outwardly with respect to the terminal end 15of input conveyor 11.

Actuating means are also provided for the stacking conveyor 21,comprising a conveyor drive motor 26. Stacker 10 includes controls forcontrolling and synchronizin g operation of both the guide actuatingmeans 25 and the stacking conveyor actuating means 26. A main controlunit 27 is mounted in the lower part of frame 12; a supplemental controlunit 28 is mounted upon an upward extension 29 of frame 12 that. alsoserves as a support for the guide actuating means 25. Stacker may alsoinclude an auxiliary guide 31 located on the opposite side of thestacking station 20 from the movable guide 24. Guide 31 is a stationaryguide, and may be omitted in some installations.

Stacker 10'further includes means for monitoring the stacking operation;this monitoring means comprises a light source 32 mounted above theinput conveyor 11 on a bracket 33 affixed to a frame member 35, asgenerally illustranted in FIGS. 1-3 and shown in greater detail in FIGS.4 and 5. A photocell 34 is positioned below conveyor 11 and is alignedwith light source 32 (FIGS. 4 and 5). For this particular monitoringarrangement, a wire mesh belt is utilized for input conveyor 11 so thatthe passage of a patty 36 through the light beam 37 between source 32and photocell 34 can be detected in the output from the photocell,enabling a part of the control system 27, 28 to obtain an accurateaccount of the patties as they are passed through the stacker. 7

In the method of the present invention, as carried out by patty stacker10, a series of frozen hamburger patties or other similar disc-shapedarticles 36 is conveyed along input conveyor 11 in flat, spaced,longitudinal alignment as shown in FIG. 2. Patties 36 are maintained inorderly rows on conveyor 11, as shown in FIG. 2, but the spacing betweenadjacent rows need not be constant. Input conveyor 11 is operated at arelatively constant speed and the path of the patties along the inputconveyor is approximately horizontal. The input path along conveyor 11terminates at the terminal end of the conveyor, from which the pattiesare discharged in free fall into stacking station 20.

As each row of patties falls from input conveyor 11, the patties arecollected in stacks on the surface of stacking conveyor 21 at thestacking location 23 below the terminal end 15 of the input path. Asnoted above, the vertical distance from the terminal end 15 of.the inputpath to the surface of the stacking conveyor 21 is chosen to allow eachpatty 36 to rotate through an angle of approximately 180 as it fallstoward the stacking conveyor (see FIG. 4). The bottom patty in eachstack rotates through an angle somewhat greater than 180 and isre-aligned horizontally as it comes to rest on stacking conveyor 21. Thetop patty in each stack rotates through an angle somewhat less than 180because its fall is interrupted before full rotation is achieved. Theaverage rotation for all patties, however, is approximately 180.

As the stack of patties accumulate in stacking station 20, the stacksare maintained in orderly alignment by the movable guide 24, which isheld steady in the stack guidance position shown in FIGS. 1 and 3. Thus,any patty that tends to fall too far outwardly away from the terminalend 15 of the input path is constrained from moving beyond the desiredstack alignment by guide 24. The stationary guide 31 may be utilized toprevent excessive movement of the falling patties in the oppositedirection from that controlled by the movable guide 24, particularly bypatties deflected by guide 24. In many-instances, however, there is notendency toward excessive movement of the patties in this latterdirection, so that the stationary guide 31 may be eliminated.

As the stacks of patties accumulate in stacking station 20, the numberof patties is counted by the monitoring means comprising light source 32and photocell 34. When a stack of desired height, such as the stack 41,has accumulated (FIG. 4), guide 24 is moved rapidly upwardly from thestacking conveyor surface and outwardly from the terminal end 15 of theinput path, as indicated by the arrow A in FIG. 4. In this manner,

7 guide 24 is shifted to a stack release position as indicated by thephantom outline 24A. At approximately the same time, the actuating meansfor the stacking conveyor 21 is activated, moving the upper surface ofthe stacking conveyor 21 in the direction of the arrow B to transportthe stack away from the stacking location 23 to the position shown forstack 41.

As soon as the stack of patties has been moved out of the stackinglocation 23 to a position clear of the stacking guide 24, the guide ismoved back downwardly and inwardly of the stacking station to itsoriginal guidance position, moving in the direction of the arrow A inFIG. 4. At about the same time, the movement of the stacking conveyor 21is interrupted and the stacking conveyor is subsequently held stationaryfor the accumulation of another stack of patties in stacking station 20.The complete cycle of operation of stacking guide 24 and stackingconveyor 21 should be accomplished before the next patty reaches theupper surface of the stacking conveyor 21, or at least very shortlythereafter, so that the first patty for the next stack will be properlypositioned in the stacking location 23.

From the foregoing description, it will be apparent that stacker l0affords an'efficient and effective apparatus for stacking patties 36, onan essentially automatic basis, eliminating hand stacking completely.The spacing between adjacent rows of the patties 36 can vary to asubstantial extent, as may occur with some interruption or minor delayin operation of the production equipment that feeds the patty stacker.Such an interruption or delay will not result in the preparation ofstacks of non-uniform height, since the stack height is effectivelycontrolled by the monitoring means comprising light source 32 andphotocell 34.

Stacker 10 serves as an in lineextensionsof the production equipment,such as the freezing tunnel 13, and requires a minimal amount of floorspace. The input conveyor 11 can be operated at quite moderate speeds,even for a high volume production line, so that the frozen patties arenot damaged or dropped when they fall from the input conveyor terminalend 15 to the stacking location 23 on the stacking conveyor 21.Consequently, breakage and loss of sanitary control are inherentlyminimized. This relatively low speed operation is made possible bypermitting the patties to rotate 7 through an angle of approximately inthe course of the stacking operation, as described above and asspecifically illustrated in FIG. 4, in contrast with the high speedoperations frequently required in stackers that maintain the patties intheir initial orientation.

A preferred construction for the stacking station 20, and particularlythe actuating means 25 for movable guide 24, is shown in FIGS. 68. Asillustrated therein,

the guide actuating means 25 is affixed to an adjustable.

L-shaped bracket 46 that is mounted upon a support 45; support 45 isaffixed to the upper frame 29 of the stacker by a plurality of bolts orother suitable mounting devices 47. A series of bolts 48 mounted inslots 49 constitute the mounting connection between bracket 46 andsupport 45, allowing horizontal adjustment of the position bracket 46parallel to the path of movement of patties through the stacker.

A channel-shaped support member 51 is mounted on the front leg 53 ofbracket 46 by suitable means such as a plurality of mounting bolts 52.The base 54 of an electrically-energized linear actuator 55, such as alinear motor or solenoid is centrally mounted within the channel-shapedsupport 51, as shown in each of FIGS. 6-8. In the illustratedconstruction, the base 54 of the linear actuator 55 is bolted to thechannel-shaped support 51, but other mounting arrangements can be utilized if desired. Support 51 is disposed at an acute angle to thevertical to provide for movement of guide 24 both upwardly and away fromstacking location 23, as described hereinafter. A sheet metal cover 56is provided for the linear actuator 55 and other components of theoperating mechanism for guide 24; the upper end of the sheet metal cover56 extends well above the linear actuator but is open at the front toallow access to a manual operating handle 57 mounted on the actuator rod58 of linear motor 55. A removable plate 59 covers an access opening 61in the lower portion of the sheet metal housing 56. V

i A bracket 62 is mounted in the support channel 51 a short distancebelow the lower end of the linear actuator 55 and a similar bracket 63is mounted in channel 51 adjacent the lower end of the channel. Thebrackets 62 and 63 can be welded to or otherwise suitably mounted withinchannel 51. Two guide rods 64 and 65 extend between and are supported bythe bracket 62 and 63, in spaced parallel relation to actuator rod 58. Abumper 66 is mounted upon the lower surface of the bracket 62 and asecond similar bumper 67 is mounted on the upper surface of the bracket63. The two bumpers 66 and 67 are formed of rubber or other relativelysoft resilient material.

The lower end of the actuator rod 58 of linear motor 55 carries atwo-piece clamp 68 and a gate mounting bracket 69. Bracket 69 is affixedto rod 58 and extends downwardly; a gate plate 71 is mounted on thelower end of the bracket. Clamp 68 is affixed to bracket 69; bracket 69includes lateral extensions that embrace the two guide rods 64 and 65.Guide 24 comprises a blade insert that is affixed to the lower end ofblade 71.

A retaining device 73 is mounted upon the support channel 51 a shortdistance below bracket 62. The retaining device 73 comprises an axiallymovable retainer rod 74 that extends through the base portion of thechannel in alignment with the actuator rod 58. Rod 74 is normallymaintained in a retracted position, out of the path of movement of theactuator rod 58 and clamp 68, as shown in FIG. 6. A handle 76 on rod 74may be employed to move the rod axially to a position in which it canengage clamp 68 and maintain the clamp and actuator rod 58 in anelevated position adjacent the upper bumper 66. A spring-biased plunger77 normally retains rod 74 in its retracted position, but a forwardthrust upon handle 76 moves rod 74 to its retaining position 74A whenrequired.

During the accumulation of a stack of patties at stacking station 20, asdescribed above in connection with FIGS. 1-5, the operating mechanism 25for guide 24 remains de-energized and guide 24 is held in the positionshown in FIG. 6. When the last patty of the stack has been dischargedover the terminal end 15 of input conveyor 11, and has fallen onto thestack, linear actuator 55 is energized through an electrical circuitcontrolled by the monitoring device comprising photocell 34 (FIGS. 4 and5). Energization of linear actuator 55 pulls actuator rod 58 upwardlyvery rapidly. The upward movement of actuator rod 58 elevates gatemounting bracket 69 moving the clamp 68 along a guided path determinedby the guide rods 64 and 65, which are parallel to the actuator rod. Inthis manner, because guide 24 is suspended from bracket 69, the guide israpidly moved from its normal stack guidance position adjacent the uppersurface of stacking conveyor 21 to its stack release position 24A (FIG.4). The upward movement of actuator rod 58, bracket 69, clamp 68, andguide 24 is interrupted by engagement of clamp 68 with the resilientbumper 66, which serves as a stop for the mechanism and also functionsas a shock absorber.

When the accumulated stack of patties has been moved clear of thestacking location 23 by a brief actuation of conveyor 21, as describedabove, linear actuator 55 is energized for movement of rod 58 in thereverse or downward direction. As a consequence clamp 68 and guide 24are driven downwardly at high speed until clamp 68 engages the lowerbumper 67. Bumper 67, like bumper 66, serves both as a stop and as ashock absorber for clamp 68 and the other components that are supportedupon actuator rod 58.

In some circumstances, it may be necessary or desirable to operate aproduction line in which stacker 10 is incorporated without attemptingto stack the articles produced by the line. For example, this may occurif the production line is changed over to the production of articles ofsome configuration not susceptible to stacking (e.g. meatballs). Underthese circumstances, handle 57 is utilized to pull actuator rod 58upwardly through linear motor until clamp 68 engages bumper 66. Inaddition, the retainer device 73 is actuated, by means of handle 76, toinsert retainer rod 74 inwardly to its position 74A, where it engagesclamp 68 to hold the clamp, actuator rod 58, and guide 24 in theelevated stack release position. This arrangement also makes it possibleto continue utilization of the production line in the event of a failureor malfunction of linear motor 55 or of any of the control equipment forthe linear motor.

The guide actuating means 25, in the form illustrated in FIGS. 6-8,affords efficient and highly effective operation for the stackingstation 20 of stacker 10. Linear motor 55 allows for rapid movement ofguide 24 -upwardly from its normal guidance position to its releaseposition and back from the release position to the guidance position.The high speed movement is essential to complete the cyclic movement ofguide 24 during a very short period determined by the time intervalbetween the discharge of two consecutive patties over the terminal end15 of the input conveyor path. The stop arrangement incorporated in theactuating mechanism 25, comprising bumpers 66 and 67, effectively allowsfor the requisite rapid operation without damage to the actuatingmechanism. The linear motor operating mechanism is substantially morereliable and effective than virtually any arrangement utilizing aconventional rotary motor. A double-acting hydraulic or pneumatic pistoncould be employed, but the electrical linear actuator is preferable fromthe standpoint of low inertia,

high acceleration, and relatively low noise level. The angled movementof guide 24, horizontally away from stacking location 23 as well asupwardly from conveyor 21, makes it possible to start the stackingconveyor before the guide completes its movement to release position,shortening the stack-completed operating cycle without havingthe stackbump against guide 24.

In many plants, particularly those producing hamburger patties, a singleproduction line may be employed to produce patties of several differentsizes. A changeover in patty size is readily accomplished, in stacker[0, by adjusting the position of bracket 46 on support 45, therebyre-positioning guide 24 for the new patty dimension. The mount foractuating means 25 may be calibrated for various standard sizes, with ascale 810m bracket 46.

For changes in thickness, the controls actuated by monitor photocell 34can readily be adjusted to trigger actuation of conveyor 21 and guide 24for a patty count commensurate with the desired stack height. Someadjustment of the positions of light source 32 and photocell 34 may benecessary to accommodate changes in the number of patties in each row;on the other hand, it is usually possible to position the monitor tofunction for any of the standard row arrangements of the productionline, since the monitor can operate as long as the light beam 37 isinterrupted by some part of a patty in each row.

We claim:

1. A stacker for stacking frozen food patties or like disc-shapedarticles, comprising:

a substantially horizontal input conveyor, having a terminal end locatedat a stacking station for conveying frozen food patties or likedisc-shaped articles to the stacking station at a predetermined speedand with predetermined minimum spacing, the input conveyor dischargingthe articles, in free fall, over its terminal end;

a normally stationary stacking conveyor, extending outwardly of thestacking station from a stacking location at a point directly below theterminal end of the input conveyor, the vertical distance from theterminal end of the input conveyor to the stacking conveyor beingsufficient to allow each article to rotate through an angle of about 180as it falls toward the stacking conveyor;

a guide, movable between a stack guidance position adjacent the stackingconveyor and a stack release position displaced upwardly from thestacking conveyor and outwardly from the stack guidance position, forguiding the articles to accumulate in an orderly stack on the portion ofthe stacking conveyor at the stacking location;

stacking conveyor actuating means for actuating the stacking conveyorfor a limited time interval, not substantially greater than the timeinterval between discharge of successive articles into the stackingstation, to transport an accumulated stack of articles away from thestacking location;

guide actuating means for actuating the guide from stack guidanceposition to release position and back again in timed relation tooperation of the stacking conveyor actuating means, the guide returningto stack guidance position before more than one article for the nextstack reaches the stacking conveyor;

and means to monitor article accumulation at the stacking location andto energize both of said actuating means when a desired accumulation hasbeen attained.

2. A stacker according to claim 1, in which the guide actuating meanscomprises a linearly movable actuator member connected to the guide andextending upwardly from the stacking location at an acute angle to thevertical, away from the stacking location, so that movement of the guideto its release position displaces the guide outwardly ofthe stackingstation and allows actuation of the stacking conveyor before the guidereaches its release position. 7

3. A stacking conveyor according to claim 2, in which the actuatormember is the actuator rod of an electrically energized linear actuator.

4. A stacker according to claim 2, in which the guide actuating meansincludes upper and lower stop mem- 1 bers defining the release and stackguidance positions of the guide, each stop member including a bumper ofresilient material positioned at one end of the path of the guidemovement to cushion the interruption of the guide movement. 7

5. A stacker according to claim 1 wherein the'monitoring means forcounting articles moving along the input conveyor and for initiatingoperation of the guide actuating means is and the stacking conveyoractuating means upon a given count.

6. A stacker according to claim 5, in which the input conveyor is a wiremesh conveyor and the monitoring means includes a light source and aphotocell aligned with each other, one above and the other below theinput conveyor.

7. A stacker according to claim 1, including a horizontally adjustablemount for the guide and guide actuating means, allowing adjustment ofthe horizontal position of the guide, toward and away from the stackinglocation, to accommodate articles of varying dimensions.

8. A stacker according to claim 1, and further comprising a supplementalstationary guide, positioned at the opposite side of the stackinglocation from the movable guide. I

9. A method of stacking frozen food patties and like disc-shapedarticles, comprising:

conveying a series of disc-shaped articles, in flat,

spaced, longitudinal alignment at a predetermined speed along a givengenerally horizontal input path toward a terminal end of the path;

discharging the articles, successively, in free fall,

from the terminal end of the input path and into a stacking station;collecting the falling articles in a stack on a normally stationaryconveyor surface at the stacking station,

at a point directly below the terminal end of the.

input path, the vertical distance from the terminal end of the inputpath to the stacking conveyor surface being sufficient to allow eacharticle to rotate through an angle of about as it falls;

guiding the articles into an orderly stack by normally maintaining aguide in a guidance position adjacent the stacking conveyor surface andspaced outwardly of the terminal end of the input path;

continuously monitoring the height of the stack of articles accumulatingon the stacking conveyor surface by counting the articles traversing theinput path;

and restoring the guide to guidance position and stopping movement ofthe stacking conveyor before the next article reaches the stackingconveyor.

10. A method of stacking according to claim 9 in which the path ofmovement of the guide is inclined at an acute angle to the vertical,away from the stacking station, and in which movement of the stackingconveyor surface is initiated before the guide reaches its releaseposition.

1. A stacker for stacking frozen food patties or like discshaped articles, comprising: a substantially horizontal input conveyor, having a terminal end located at a stacking station for conveying frozen food patties or like disc-shaped articles to the stacking station at a predetermined speed and with predetermined minimum spacing, the input conveyor discharging the articles, in free fall, over its terminal end; a normally stationary stacking conveyor, extending outwardly of the stacking station from a stacking location at a point directly below the terminal end of the input conveyor, the vertical distance from the terminal end of the input conveyor to the stacking conveyor being sufficient to allow each article to rotate through an angle of about 180* as it falls toward the stacking conveyor; a guide, movable between a stack guidance position adjacent the stacking conveyor and a stack release position displaced upwardly from the stacking conveyor and outwardly from the stack guidance position, for guiding the articles to accumulate in an orderly stack on the portion of the stacking conveyor at the stacking location; stacking conveyor actuating means for actuating the stacking conveyor for a limited time interval, not substantially greater than the time interval between discharge of successive articles into the stacking station, to transport an accumulated stack of articles away from the stacking location; guide actuating means for actuating the guide from stack guidance position to release position and back again in timed relation to operation of the stAcking conveyor actuating means, the guide returning to stack guidance position before more than one article for the next stack reaches the stacking conveyor; and means to monitor article accumulation at the stacking location and to energize both of said actuating means when a desired accumulation has been attained.
 2. A stacker according to claim 1, in which the guide actuating means comprises a linearly movable actuator member connected to the guide and extending upwardly from the stacking location at an acute angle to the vertical, away from the stacking location, so that movement of the guide to its release position displaces the guide outwardly of the stacking station and allows actuation of the stacking conveyor before the guide reaches its release position.
 3. A stacking conveyor according to claim 2, in which the actuator member is the actuator rod of an electrically energized linear actuator.
 4. A stacker according to claim 2, in which the guide actuating means includes upper and lower stop members defining the release and stack guidance positions of the guide, each stop member including a bumper of resilient material positioned at one end of the path of the guide movement to cushion the interruption of the guide movement.
 5. A stacker according to claim 1 wherein the monitoring means for counting articles moving along the input conveyor and for initiating operation of the guide actuating means is and the stacking conveyor actuating means upon a given count.
 6. A stacker according to claim 5, in which the input conveyor is a wire mesh conveyor and the monitoring means includes a light source and a photocell aligned with each other, one above and the other below the input conveyor.
 7. A stacker according to claim 1, including a horizontally adjustable mount for the guide and guide actuating means, allowing adjustment of the horizontal position of the guide, toward and away from the stacking location, to accommodate articles of varying dimensions.
 8. A stacker according to claim 1, and further comprising a supplemental stationary guide, positioned at the opposite side of the stacking location from the movable guide.
 9. A method of stacking frozen food patties and like disc-shaped articles, comprising: conveying a series of disc-shaped articles, in flat, spaced, longitudinal alignment at a predetermined speed along a given generally horizontal input path toward a terminal end of the path; discharging the articles, successively, in free fall, from the terminal end of the input path and into a stacking station; collecting the falling articles in a stack on a normally stationary conveyor surface at the stacking station, at a point directly below the terminal end of the input path, the vertical distance from the terminal end of the input path to the stacking conveyor surface being sufficient to allow each article to rotate through an angle of about 180* as it falls; guiding the articles into an orderly stack by normally maintaining a guide in a guidance position adjacent the stacking conveyor surface and spaced outwardly of the terminal end of the input path; continuously monitoring the height of the stack of articles accumulating on the stacking conveyor surface by counting the articles traversing the input path; moving the guide upwardly of the stacking conveyor surface and outwardly of the terminal end of the input path to a stack release position upon accumulation of a stack of given height; moving the stacking conveyor surface to transport the stack away from the stacking location, substantially simultaneously with movement of the guide toward its release position and in response to monitoring a predetermined height of articles on the stacking conveyor; and restoring the guide to guidance position and stopping movement of the stacking conveyor before the next article reaches the stacking conveyor.
 10. A method of stacking according to claim 9 in which the path of movement Of the guide is inclined at an acute angle to the vertical, away from the stacking station, and in which movement of the stacking conveyor surface is initiated before the guide reaches its release position. 